Finishing-broach.



R. R. LAPOINTE.

FINISHING BROACH.

APPLICATION EILED 02cm I915.

Patented m 5,1916.

A AF

RALPH R. LAPOINTE, OF HUDSON, MASSACHUSETTS, ASSIGNOR TO THE LAPOINTE MACHINE TOOL COMPANY, OF HUDSON, LMASSACHUSETTS, A CORPORATION OF MAINE.

FINISHING-BROACH.

Application filed December 7, 1915.

T 0 all whom it may concern:

Be it known that I, RALPH R. LAPOINTE, a citizen of the United States, and resident of Hudson, county of Middlesex, Commonwealth of Massachusetts, have invented an improvement in Finishing-Broaches, of which the following description, in connection with the accompanying drawings, is a specification, like characters on the drawings representing like parts in each of the several views.

This invention relates to broaches of a type specially adapted for finishing a broached hole equipped with a plurality of spaced apart key seats radiating therefrom. In producing such holes with multiple key seats, a specially practicable and convenient method consists in rapidly rough drilling the holes, or producing the same in the rough in any other convenient manner and then to produce the multiple key seats by a broaching tool which has a central core portion guided more or less loosely in the previously rough drilled hole. This method of pro cedure results in more or less unevenness and inaccuracy of the central hole with respect to the multiple key seats, though the multiple key seats themselves are necessarily accurate and correctly formed with respect to one another, sinpe they are all produced by a single movement of the same broachin tool.

%he prime object of the present invention is to provide a finishing broach adapted for sizing and accurately finishing the central hole with respect to the multiple key seats previously formed therein by the key seating broach. To this end I provide a broach equipped with spaced apart spider or ribbed guiding portions adapted to fit into and be guided by the multiple key seats in the work, and having between such guiding portions broaching ring portions adapted to engage and operate on the rough and uneven periphery of the central hole to finish the same and render the central hole accurate and correctly centered with respect to the seve al key seats. in accordance with a fureature oi? the invention these finishing breaching ring portions may be formed to Specification of Letters Patent.

Patented dept. 5, i916.

Serial No. 65,601.

finish and slightly round the corners where the key seats join the central hole, and cer tain of the ribbed guiding portions may be formed to smooth or slightly finish the key seats if desired.

The present invention may be embodied either in a broach of integral construction or in one where the several guiding and breach finishing portions are fitted on a central rod or bar; both forms being shown in the drawings. i

The invention will be better understood from the following detailed description taken in connection with the accompanying drawings and will be thereafter pointed out in the appended claims.

Referring to the drawings: Figure 1 shows in side elevation an integral broach constructed in accordance with my invention, intermediate portions being broken away; Fig. 2 is an elevation showing the central rod or bar of a built up broach constructed. in accordance with my invention, intermediate parts being broken away; Fig. 3 is an elevation of a built up broach adapted tobe assembled on the rod or core of Fig. 2, intermediate portions being broken away; Fig. 4 is a cross section on line 4-4 of Fig. 1; Fig. 5 is a cross section on line 5-5 of Fig. 1; Fig. 6 is a cross section on line (i6 of Fig. 3; Fig. 7 is a cross section on line 77 of Fig. 3; and Fig. 8 is an end view of the guiding element shown at the left of Fig. 3.

In the integral hroach of Fig. 1 a Shank portion 10 of a size to fit easily into the rough drilled hole, is followed by a guide portion 11 having a. series of radial ribs or spider projections 12 spaced apart and formed to fit into the several key seats previously broached in the work. In practice these ribs 12 are formed to (it the bottoms of the key seats, and where there is a relatively small number of key seats they are formed to fit the sides thereof also; in cases where there are a. relatively large number of ke Y slots c. ten or more. it is only neces- 7 1 sary that the ribs should ht the bottoms ot such slots in order to perform their guiding function proyjie y. The entrance end of these ribs may be slightly rounded as indicated at 13 to facilitate the entrance thereof into the key seats. This guide portion is followed by a series of broaching ring portions 14 adapted to act on to true and finish the rough drilled central hole. In practice this rough drilled hole is preferably made about one-sixteenth inch smaller than the size to which,it is to be finished so as to allow for any degree of inaccuracy apt to be encountered. This series of broaching rings 14 is followed by another guide portion 15 suitably spaced from the first guide portion 12 according to the thickness of the work and other considerations. This is followed by other series of broaching rings 14: with interposed guide portions and another similarly spaced guide portion 16, and still another broach ring portion 14 with another guide portion 17, and others as required until the broach is extended to the requisite length for performing the required broach finishing operation at a single movement thereof as is usual. The finishing end of the broach may be equipped with a long smooth drift 18, formed to the complete section of the finished hole including the key seats adapted to smooth and impart a high burnishing finish to the broached hole. In practice certain of the spider or ribbed guide portions may be formed to finish and true to size the sides of the key seat slots. For this purpose I show certain of the guide portions with squared entrance corners adapted for cuti718 indicated at 19 on the guide portions For'producing a built up broach a rod or bar 20 shown as circular in cross section is provided and equipped with a longitudinal spline 21. This bar has at one end an operating shank portion 22 merging into thebar proper in a reducing shoulder 23 against which the broach elements are fitted, the other. end of the bar being screw threaded as indicated at 21. On this core rod or bar are fitted broaching and guiding elements similar to those already described, each of these elements being equipped With a key way 25 to fit the spline or key 21, and hold the elements in circular alinement. An entering guide member is indicated at 26 which may be. similar to the guide portion 12 and followed by other guide portions '26, 26*, 26, etc., alternating with cutting ring portions 27 adapted to true and finish the central hole as already described. 'I may form .c'ertain of the cutting ring p01- tions to 1}), fl and finish the corners where the ko seats" join'the central hole. For this purpbse J show some of the intermediate cutting rings 27. formed with small projections adapted to operate on said corners to smooth and slightly round them to the requisite extent. The broaching and engage only alternate seats.

guiding elements thus constituted may be held assembled on the body or core by a nut 29 engaging the threaded end 21 of the core. The ribs on the guide portions of the broach may correspond in number to the number of key seats in the work, or where the number of key seats is very large the number of guide ribs may be such as to Thus in the integral broach of Fig. 1, only five guide ribs are shown while the drift 18 which exhibits the complete cross section of the hole with all the key seats is formed to cooperate with a hole having ten key seats.

It is of course to be understood that where I refer to the series of spaced apart radial key seats in the present description, this is merely illustrative and intended to typify any spaced apart slots or grooves extending from a central hole adapted to receive broach guiding portions for holding true, broaching elements to size and finish the central hole. I further desire the present embodiment to be considered as illustrative and not restrictive in all respects, referring rather to the appended claims than to the foregoing description to indicate the scope of the invention. 1

Having described my invention, what I claim as new and desire to secure by Letters Patent is:

1. A broach, comprising a guide portion having a plurality of projections adapted to engage in spaced apart key seats for guiding the broach, and cutting portions following said guide portion for sizing and finishing the central hole in the work.

2. A broach, comprising a plurality of spaced apart guide portions, each having projections adapted to fit in spaced apart key seats to guide the broach, and scries'of cutting portions between said guide portions adapted to size and finish the central hole in the work.

3. A broach, comprising a plurality of guide portions, each formed with a series of radial ribs adapted to fit in spaced apart key seats to guide the broach, and a series of cutting elements between said guide portions adapted to gradually size and true the central hole of the work with reference to said key seats.

4. A broach, comprising a series of guide portions spaced apart along the length thereof, each having projecting ribs adapted to fit in spaced apart key seats to guide the broach, and cutting rings between said guide portions adapted to gradually size and true the central hole of the work with reference to said key seats, certain of said cutting rings having formations to finish and slightly round the corners between said guide seats and the central hole of the work.

5. A broach, comprising a series of spaced memes apart guide portions, each having projectguide ribs having their Mvance ends ing ribs adapted to fit in spaced apart key formed. to finish saidl key seats.

seats to guide the broach and'euttin por- In testimony whereof, 1 have signeti my tions between said; guide portions a epted name to this specification. to finish and true the central hole with reterence to saiei key seats, certain of said RALPH R. LAPOINTE, 

